The invention relates to a heat sink, particularly for the cooling of electronic structural elements, having a base body on which the structural elements and a cooling element that carries off heat are arranged next to one another.
Heat sinks of this type are known and, as a rule, consist of aluminum extruded sections. In this case, a base plate that is developed as a base body has cooling projections developed as ribs that are connected in one piece with the base body and represent the cooling element. This heat sink is manufactured in the extrusion process and is therefore limited with respect to design possibilities and different receiving possibilities for the structural elements. As a result of the manufacturing process, thin high ribs with a simultaneously narrow rib distance are not possible. This has the result that heat sinks of this type, relative to their overall size, have relatively small heat transmission surfaces.
Another known heat sink, described in German Published Unexamined Patent Application No. (DE-OS) 35 00 976, provides that on a base plate, several cooling projections are provided that have a fastening flange. These cooling projections may, for example, consist of thin sheet-metal strips that, next to one another, at the distance of their fastening flange, are connected with the base plate via a welded connection. As a result of the fastening flanges that must have a suitable width, because of the welded connection, the cooling projections cannot be packed arbitrarily densely. This heat sink also has the disadvantage that the cooling projections must be fastened at the base plate successively which is time-consuming and cost-intensive.
An objective of the invention is to provide a heat sink that can be adapted individually to the special cooling problems occurring in electrical equipment, that, relative to its overall size, has a relatively large heat transfer surface and can be manufactured in an uncomplicated way.
According to the invention, this objective is achieved by the fact that the cooling element is developed as a bundle of ribs consisting of a plurality of sheets, the sheets being arranged essentially in parallel and a distance to one another that is determined by the thickness of the plates of the bundle of ribs. These sheets are connected with one another at one of their longitudinal sides and the bundle of ribs is connected with the base body in a material connecting or locking manner such as by soldering.
The heat sink according to the invention has a base body on which the structural elements to be cooled are arranged, for example, in an edge area. Adjacently, the cooling element is arranged that is connected with the base body in a material connecting manner such as by soldering. This cooling element consists of sheet metal plates, the individual plates having a distance to one another. The sheets may be held, for example, via a soldered bridge or the like so that they are located at a specified distance from one another and are also connected with one another in a material connectinq manner and form a bundle of ribs, namely the cooling element. This bundle of ribs, in turn, is connected with the base body in a material connecting manner. By means of the suitable selection of the spacing of the individual sheet metal plates, of the thickness of the plates and of the dimensioning of the plate surfaces, the cooling element may be developed in such a way that on the one hand, it has the required base surface so that sufficient space still exists for the fastening of the structural elements and, on the other hand, it possesses the required heat transfer surface in order to reliably carry off the heat that is generated by the structural elements. By means of the variation of the number of sheets as well as their size, their spacing and their thickness, whereby the sheet density of the bundle of ribs is determined, an optimal design of the cooling element is easily possible.
The material connection of the cooling element with the base body, in addition to the merits of other undetachable connections, has the advantage that the whole heat sink possesses the heat transfer characteristics of a one-piece body. No hollow spaces or heat-insulating inserts exist between the base body and the cooling element that could impair the flow of heat.
An easy varying of the distance between the individual sheets is achieved by providing between the sheets intermediate sheets that determine the gap width. The thickness of the intermediate sheets determine the distance between the individual sheets that carry the heat away from the base body.
Preferably, the intermediate sheets are arranged at a longitudinal side of the sheets and are connected with them in a material connecting manner. The sheets, by means of the inserting of the intermediate sheets, can be built into the finished cooling element that subsequently must only still be connected with the base body.
Advantageously, the material connection of preferred embodiments is a soldered connection, preferably a flux-free soldered connection. By means of the arrangement of the intermediate sheets at a longitudinal side of the sheets and by means of the material connection with these, the cooling element that is developed as a bundle of ribs offers a suitable contact surface, via which it can be connected with the base body. The flux-free soldered connection offers the advantage that, as a result of the wetting characteristic of the solders and of the suction effect of the capillary gaps, it offers a large-surface connection of the surfaces that rest against one another. By means of a soldered connection, cooling elements with large dimensions can also be fixed on the base body without hollow spaces and without inserts or inclusions. The material connection of the individual components among one another ensures an optimal heat transmission and heat flow between the base body and the cooling element. The heat is transmitted to an air flow that is directed in parallel to the sheets and flows through the cooling element.
Preferred embodiments provide that the cooling element is constructed of L-shaped, T-shaped or U-shaped sheets that, in the area of their projections or crossbars, for receiving additional structural elements, forming a contact surface, are connected with one another in a material-locking way via intermediate sheets. In this case, the intermediate sheets that are arranged between the L-shaped and T-shaped sheets and hold them at a distance from one another, are advantageously provided in the area of the projections of the sheets, so that a massive crossbar is created. The thus formed crossbar that projects from the cooling element may serve as an additional contact surface for structural elements. In the case of a T-shaped development of the sheets, two crossbars for the additional receiving of structural elements are obtained that are arranged on opposite sides of the cooling element. In the case of U-shaped sheets, a massive crossbar for receiving the structural elements is obtained that connects the free legs of the sheets.
In the case of special installation conditions, it is advantageous for the sheets to be arranged diagonally with respect to the edges of the base body. As a result of the diagonal position of the sheets, in which case these continue to be disposed in parallel to one another, the heat sink may be adapted, for example, to a specified air guidance in an electronic device unit so that a high heat transmission continues to be achieved.
Further preferred embodiments provide that the cooling element is part of a bundle of ribs that consists of a plurality of L-shaped, T-shaped or cross-shaped sheets, in which case the sheets are connected with one another in a material-locking way essentially in parallel to one another and, in their area having the projections, via intermediate sheets. The projections that are connected with one another via the intermediate sheets form the base body that receives the structural elements and the remaining bundle of ribs forms the cooling element. The base body is now formed by the projections that are connected with one another via the intermediate sheets. By adding additional intermediate sheets to the two extreme sheets, a surrounding edge can be formed that receives the structural elements. In the case of the cross-shaped sheets, the cooling element extends at both sides of the base body.
Another embodiment provides that the sheets are developed as at least one corrugated rib strip. This corrugated rib strip has the advantage that it can be connected immediately with the base body because the individual parallel sheet sections are already spaced away from one another. This corrugated rib strip is fixed on the base body in such a way that it rests against the base body with its corrugation arches, so that the air flow can pass through unhindered between the individual sheet sections. The corrugated rib strip and the base body are connected with one another in a material-locking way. An increase of the heat flow is caused by filling out the wedge-shaped gaps between the corrugation arches and the base body with solder.
In order to increase the heat transmission, two or more corrugated rib strips are provided. In this case, it is advantageous for one corrugated rib strip to have a cover sheet at the side that faces away from the base body, another corrugated rib strip being arranged on this cover sheet. A further increase of the heat transmission is achieved by the mounting of additional corrugated rib strips that are arranged above one another in such a way that between them, only one cover sheet is provided that is used for the conduction of heat within the cooling element and carries the fitted-on corrugated rib strip.
Advantageously, the base body and/or the cover sheets are coated with a soldering material or carry a soldering foil for accommodating the material locking connection.
A compact heat sink is obtained by the fact that the base body projects over the cooling element on all sides. The structural elements may be provided on the side that carries the cooling element as well as on the opposite side. In addition, the base body may be equipped either with a cooling element that is arranged on one side, or both sides may carry cooling elements. If necessary, the cooling element may also frame the component or components.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.